addresses the nation, wolf. >> it looks like this may be the worst mass killing at a school in u.s. history, based on the information i'm getting over here. columbine high school, littleton, colorado, back in 1999, dylan klebold and eric harris killed 12 fellow students and one teach brother before committing suicide in the school library. in this case, john king reporting close to 30, we believe, are now dead. and 18 to 20 of them children, if those numbers hold up. this looks like it could be the worst mass killing in american history, something no one anticipated would be happening at any point, but listen to the white house press secretary jay carney speak about this, just a little while ago. >> the president was notified by his homeland security adviser, john brennan, of the shooting in newtown, connecticut, at a school. the president is receiving regular updates as more information becomes available about this incident. and as the day proceeds, if we get more information and as we get more information, we'll certainly provide it to you. i do not have anything to confirm for you at thi